Electrically controlled hydraulic turret press



July 22, 1941. P. .1. LINDNER 2,249,964 ELECTRI CALLY CONTROLLEDHYDRAULIC TURRET PRESS Filed Aug. 16, 1958 10 Sheets-Sheet 1 as A A.fnverztor .PH/L/P J. Ll/YD/IEI? Attorney:

July 22, 1941.

P. J. LINDNER ELECTRICALLY CONTROLLED HYDRAULIC IURRET PRESS 10Sheets-Sheet 2 Filed Aug. 16, 1958 l/vvziwroe PHIL/F J. Amp/v5 B BYATTOENEYS July 22,1941. P. J. LINDNER "2,249,954

ELECTRICALLY CONTROLLED HYDRAULIC TURRET PRESS Filed Alig. 16, 1938 10Sheet'S -Sheet 3 llvvz/vroza PH/L/P J. LINDA/EB 5v [3 1 Arromvzvs In]?22, 1941. P. J. LINDNER ELECTRICALLY CONTROLLED HYDRAULIC TURRET PRESSFiled Aug. 16, 1938 10 Sheets-Sheet 4 IQTTOIQNEYS July 22, 1941.

P. 4. LINDNER ELECTRICALLY CONTROLLED HYDRAULIC T URRET PRESS l0Sheets-Sheet 5 Filed Aug. 16, 1938 'llllll llllllirlllllllllll IIIL JILINVENTOB P/J/L/P J. Lum/ws/e A T TOENE vs Jul 22, 1941. P. J. LINDNERELECTRICALLY CONTROLLED HYDRAULIC TURRET PRESS Filed Aug. 16, 1938 l0Sheets-Sheet 6 //v VE/Y 7oz PHIL/P L wo/vee July 22, 1941. P. J. LINDNERELEGTRICALLY CONTROLLED HYDRAULIC TURRET PRESS l0 Sheets-Sheet 7 FiledAug. 16, 1938 flrroelvcys July 22, 1941.- P. J. LINDNER 2,249,964

ELECTRICALLY CONTROLLED HYDRAULIC TURRET PRESS Filed Aug. 16, 1938 10Sheets-Sheet 8 .fmrentor PHIL/P J. L/ND/YEI? imfilwiw A) T ttorneys@mfly 2, WM P. J. LINDNER 2,249,954

ELECTRICALLY CONTROLLED HYDRAULIC TURRET PRESS Filed Aug. 16, 1938 10Sheets-Sheet l0 flttarrzeys frwen tor 5J0 PHIL. /P J. L/ND/YE/P PatentedJuly 22, 1941 ELECTRICALLY CONTROLLED HYDRAULIC TURRET PRESS Philip J.Lindner, Mount Gilead, ohio assignor to The Hydraulic Development Corp.Inc., Wilmington, Del., a corporation of Delaware Application August 16,1938, Serial No. 225,250

27 Claims.

This invention relates to presses and press control systems, and inparticular, to turret presses having rotary turrets for feeding theworkpieces to the press.

One object of this invention is to provide a turret press having meansfor removing the load of the turret from its bearings during thepressing operation, and utilizing the bearings only during the rotatingor indexing operations.

Another object is to provide a turret press, wherein the turret isarranged to be supported upon the bed of the press out of engagementwith its rotary bearings during the pressing operations, and havingmeans for bringing the bearings into contact with the turret so as tofree the turret from its engagement with the press bed during therotating and indexing operations, thereby relieving the turret bearingsand turret revolving mechanism 01 all strain during the pressingoperations, and to effect the sustaining of this strain by the press beditself.

Another object is to provide a turret press having means forautomatically loosening or ejecting the workpiece from the die after thepressing operation, this means being synchronized {or automaticoperation at the conclusion of the pressing operations without thenecessity for attention thereto upon the part of the operator.

Another object is to provide a turret press having means for alternatelyplacing a plurality of separate dies in the working position at a giventurret station, so as to perform two separate pressing operations insequence upon the workpiece.

Another object is to provide a control system for a turret press, asdescribed in the preceding paragraph, wherein the motion of the two diesis synchronized with the motion of the press ram so as to insure thatthe proper press die will be completely in position before the press ramis permitted to perform its pressing stroke.

Another object is to provide a turret press having mechanism cooperatingwith the Workpiece loosening or ejecting means for hoisting theworkpiece out of the turret after the loosening or ejecting has takenplace.

Another object is to provide a turret press having means for effectingthe various movements of the press elements in timed sequenceautomatically, without the necessity for attention thereto by theoperator or for dependence upon his judgment, such movements, forexample, including the rotation of the turret, the motion of the turretlocking device, the motion of the turret bearing raising and loweringmechanism, the motion of the die carrier to its different positions andthe operation of the pressing platen.

Another object is to provide an interrelated electrical control systemfor automatically controlling the movments of the turret press elements,as set forth in the preceding paragraph.

Another object is to provide an electrical control system for turretpresses, wherein means is provided for preventing the occurrence of theFigure 1 is a front elevation of a turret press embodying theimprovements of the present invention, looking toward the strain rodabout which the turret revolves.

Figure 2 is a right-hand side elevation of the turret press shown inFigure 1, with one of the turret raising cylinders and the ejectorcylinder I shown partly in section.

Figure 3 is a transverse vertical section taken along the line 3-3 inFigure 1, except that for convenience of showing of the hydrauliccircuit the pump ejector cylinder and one of the turret raisingcylinders are shown in side elevation rather than in section.

Figure 4 is a horizontal section through the press, taken along the line4-4 in Figure 2, with portions of the turret broken away to disclose themechanism thereunder more clearly.

Figure 5 is an enlarged front elevation, partly in section, showing theturret locking mechanism as shown in the lower portion of Figure 1.

Figure 6 is an enlarged detail view, partly in section, of theturret-lifting mechanism shown at the bottom of Figure 3, assuming thatthe tur ret has been revolved during the indexing movement to a pointwhere the center line of a turret station coincides with a center lineof one of the lifting cylinders before the turret station reaches thepressing position.

Figure '7 is an,enlarged side elevation, partly in section, similar tothe central portion of Figure 2 and showing the hoisting mechanism forhoisting a workpiece out of the turret after it has been loosened orpartially ejected.

Figure 8 is an enlarged side elevation, mainly in section, showing theejecting or workpieceloosening mechanism located immediately below thehoisting mechanism of Figure 7, and in effect, forming a continuation ofFigure 7.

Figure 9 is a longitudinal section through the main cylinder relief andby-pass valve shown in the surge tank at the top of Figure 3.

Figure 10 is a cross section along the line I0I0 in Figure 9.

Figure 11 is an elementary wiring diagram showing the various electricalelements and connections in the electrical control circuit of the turretpress of this invention.

Figure 12 is a wiring diagram showing the same circuit as in Figure 11,but with the various switchblades of each relay or contactor arrangedadjacent one another to show their operation more clearly.

Figure 13 is a diagrammatic cross section through a typical workpiece,ready for the first pressing operation in the turret press of thisinvention.

Figure 14 is a view similar to Figure 13, but

4 showing the workpiece after the completion of the first pressingoperation and'ready for the second pressing operation.

Figure 15 is a view similar to Figures 13 and 14, but showing theworkpiece after the completion oi the second pressing operation andready to be ejected from the press.

General arrangement In general, the turrret press of this inventionconsists of a press frame having a bed and a head interconnected bystrain rods, the arrangement of three strain rods being preferablebecause it enables one of the strain rods to be used as the fixed shaftabout which the turret is rotated. The turret is normally supported uponthe bed of the press during the pressing opera tions, but is raised fromthe press bed and into engagement with anti-friction bearings during itsrotating or indexing operations. After the indexing operations arecompleted, the turret is brought to rest upon the press bed, therebyremoving the load from the turret bearings so that the press bed and notthe turret bearings sus tains the thrust of the pressing platen duringthe pressing operations. A movable die carrier is provided foralternately placing two separate upper dies in the working position at agiven turret station so as to perform two separate pressing operationsin sequence upon the workpiece.

A hydraulic motor is provided for raising and lowering the turretrelatively to the press bed and the turret supporting bearings. A springcontrolled by an electromagnetic device is provided for operating theturret locking member by which the turret is locked in position afterbeing indexed to its working position at a given station, and during thepressing operation. A second hydraulic motor is provided for looseningor ejecting the workpiece from the turret, and a fluid pressure motorcooperates therewith for hoisting the thus loosened workpiece out of theturret. Still another fiuid pressure motor is provided for shifting thedie carrier to and fro, so as to present its dies sequentially in theirworking positions. A direct current motor is provided, together with anappropriate electrical circuit, for rotating the turret during itsindexing operations, and for dynamically slowing down and vided forperforming the pressing operations upon the workpieces, and a suitablehydraulic circuit is provided for supplying pressure fiuid to thevarious motors. An electrical circuit is likewise provided andinterrelated with the hydraulic circuit for causing the variousoperations of the press to take place automatically and in the propersequence. Certain electrical devices, such as interconnected contactorsor relays, are provided for preventing the motion of the variouselements except at their proper times and to their proper positions,thereby relieving the operator of the necessity of devoting hisattention or judgment thereto.

Mechanical construction Referring to the drawings in detail, Figure lshows one embodiment of the turret press of this braking the turret asit approaches a given indexing position. A main hydraulic motor,consisting of a main cylinder and plunger, is proinvention as includinga press head '0 and a press bed I I, interconnected by strain rods I2with nuts I3 threaded upon the ends thereof. The strain rods I2 arethree in number, the central one having a turret assembly, generallydesignated I4, rotatably supported thereon, as hereinafter described indetail. Reciprocably mounted upon the strain rods I2 is a platen I 5,connected by the split ring I6 (Figure 3) to the main plunger I! at thegroov I8 therein. The platen I5 is guided upon the strain rods I2 bymeans of the precision boredsplit bushings I9, held in place by the caps20 bolted to the platen l5. The space between the caps 20 and the splitbushings I9 is filled by an annular ring of Babbitt metal 2 I, which iscast around the split bushings I9 after the caps 20 are bolted inposition. By this arrangement the split bushings I9 are properly locatedwithrespect to the remainder of the press, and no cramping actiontherefore occurs.

Surrounding the main plunger I1 is a packing 22 arranged to becompressed by a gland 23, bolted to the head III of the press. The mainplunger IT is illustrated as being double-acting in that it isreciprocable within a cylinder bore 24 formed in the main cylinderportion 25 of the press head I 0, and has a piston head 26' witharrangements for admitting pressure fluid on the opposite sides thereof.The main cylinder 25 is provided for this purpose with upper and lowerports 21 and 28, from which the conduits tively to the forward andreturn connections 3| and 32 of the reversible variable delivery pump33. The piping shown in Figure 3 is rearranged slightly from that shownin Figure 2 in order to show the entire course thereof and to discloseportions of the piping which are concealed by portions of the press inFigure 2.

Communicating with the conduit 30 and return connection 32 is a conduit34, having a branch 35 connected to the operating cylinder 36 of thesurge valve, generally designated 31. The latter is mounted within thesurge tank 38 on top of the press head I0, and is of the type disclosedin the Ernst Patent No. 1,892,568, issued Dec. 27, 1932. The surge valve31 consists of a casing 39 (Figure 3) bolted to the main cylinder 25,and having a sleeve 40 disposed in a port 4| interconnecting the top ofthe main cylinder bore 24 and the interior of the surge tank 38.Reciprocable within the sleeve 40 is a surge valve plunger 42 having anenlarged portion 43, urged upwardly into a closing position by means ofthe coil spring 44. The

29 and 30 lead respectop of the main cylinder bore 24, and to draw fluidthrough the ports 45'and 46 and through the interlor of the sleeve 40.The valve plunger 42 isprovided with flutes to permit the'ffipassage ofthe fluid thereby. The bottom of the sleeve 40 is closed by a disc 48,serving alsoas an abutment for the lower end of the coil spring 44. Thedisc 48 and the lower end of the sleeve 40 rest within a recess 49 inthe upper end of the main'plunger I! when the latter is in its upper orretracted position.

In order to hold open the valve plunger during the return stroke of themain plunger H, the surge valve casing 39 is provided with an auxiliaryplunger 58 reciprocable within a bore5l, closed by the cylinder head52and having a port 53 for the connection of the conduit 35. The auxiliaryplunger 50 is urged upwardly by the coil spring 54.

The surge valve 31 serves the purpose of prefilling the main cylinderbore 24 during the forward stroke of the main plunger IT as the lattercoasts downwardly under the influence of gravity. The surge valve 31closes automatically against the surge valve seat 55 when the platen I5meets with resistance to its forward motion. The pressure built upwithin the upper part of the main cylinder bore 24 closes the surgevalve 31 by urging its plunger 42 upwardly, aided by the force of thecoil spring 44. The main plunger I! thereafter ceases to draw in fluidfrom the surge tank 38, and the pressure is therefore built up by meansof the pump 33 sufllcient to complete the pressing stroke.

When the pump 33 is reversed, however, so ,that it supplies pressurefluid to the return line 3!! '(Figures 2 and 3), pressure fluid reachingthe auxiliary cylinder bore 36 within the surge valve 31 forces theauxiliary plunger 58 downwardly, and forcibly holds open the surge valveplunger 42. During the return stroke of the main plunger II, as broughtabout by pressure fluid entering the port 28 beneath the piston head 28,the fluid within the upper part of the main cylinder bore24 above thepiston head 26 is enabled to escape through the ports 45 and 46 directlyinto the surge tank 38. Mounted on top of the surge tank 38 is a boss56, surrounding a port 51 in the surge tank cover 58, and serving toreceive an air fllter 59 (Figure 2) for excluding dirt and'dust from thesurge tank 38. The surge tank ordinarily contains a cooling coil (notshown) through which cold water may be circulated in order to carry offthe heat which has developed in the working fluid, usually oil, byfriction in the pump 33 and hydraulic circuit connected thereto.

Mounted upon the upper end of the conduit 34, vimmediately above itsconnection with the branch conduit 35, is a. relief valve 60. A similarrelief valve BI is mounted on the end of the branch conduit 62 connectedto" the conduits 63, which communicates with the forward conduit 29. InFigure 3 the conduit 63, for simplicity and clearness, is shown ascoming directly out of the forward pressure connection 3| of thevariable delivery pump 33, instead of being concealed within the maincylinder 25 according to the showing in Figure 2. Connected to thebranch conduit 62 is the main cylinder relief and by-pass valve 64(Figure 3) having the conduit 65 connecting it to the conduit 34. Themain cylinder relief and by-pass valve 64 is shown in detai in Figures 9and 10. Its details,however,, form no part of the presentinventionbut'are fully disclosed in the Ernst Patent No. 1,956,758,issued May 1, 1934. The valve 64 is an automatic valve serving thepurpose of releasing the pressure from the main cylinder bore 24 abovethe piston head 26 at theinstant of reversing the pump 33 to An ordinarycheck valve 68 (Figure 3), hav-' ing a ball 61 closing a port 68, isconnected to the conduit 34 and serves to prevent the passage of fluidtherethrough into the surge tank 38 during the return stroke of thepress,. while permitting the withdrawal of fluid therefrom during theforward stroke of the press. Connected to and communicating with theforward and return conduits 29 and 30 are the auxiliary conduits 69 and10, respectively. These lead to the ejection and turret raising motors,as hereinafter disclosed. In order to limit the stroke of the mainplunger I! and platen I5, the strain rods l2 are provided with annularridges and grooves 'H and 12,respectively engaged by the correspondinglyridged and grooved collars 13. This construction enables these collarsto sustain a tremendous load and prevent'overstroke in the event thatthe press should be operated without dies. The interlocking ridge andgroove construction distributes the load and adds to the strength of theassembly.

Bolted to the underside of the main platen I5 is the die carrier support14, having retaining members 15 bolted thereto and adapted to retain inthe guideway-l8 thereof the die carrier 11 (Figures 3 and 4). The diecarrier 11- carries two clamping rings 18, each capable of holding adie. The die carrier 11 is reciprocated by means of the piston rod 19(Figure 4), secured thereto as at 88 and having a double-acting pistonhead 8| reciprocable within the cylinder 82. The die carrier cylinder 82is mounted upon the bracket 83 (Figures 1 and 4) depending from theplaten 15. Pressure fluid, such as compressed air,'is supplied to theOpposite ends of the cylinder 82 through the conduits 84 and 85 leadingto the die carrier control valve 86, to which compressed air is suppliedthrough the branch conduit 81 from the compressed air supply conduit 88.The die carrier control alve 86 is actuated in one direction by theelectrical solenoid 89, and in another direction by a spring therein(not shown). The conduits 84 and 85 are flexible so as to maintaincommunication while the platen l5 and the die carrier cylinder 82 arereciprocating, the die carrier control valve being bplted to the presshead l8 (Figure 1). Ajmanual air shut-off valve enables the manualcontrol over the supply of air to the die carrier control valve 86.

The conduit 88 is supplied with compressed air from any suitablecompressed air source (not shown) by way of the conduit 9| (Figure 2).

"Leading from the conduit 9| 0n the opposite the hoisting cylinder I03,containing a doubleiiacting air-operated piston (not shown) upon apiston rod 104. Threaded into the lower end of the piston rod I04 is anadjusting rod I05, which in turn, is threaded into the yoke I06 havingthe pivot shaft I01 mounted in the bracket I08 thereof (Figure 7).

Pivotally mounted upon the pivot shaft I01 ffkare the gripper arms I09,urged downwardly by the coil springs H surrounding the guide studsIII,'- which are threaded into the gripper arms I09. The-studs III passloosely through aper tures H2 in. the yoke I06, and on their upper endscarry .the stop nuts I3 for limiting the motion of 'the' gripper armsI09. The yoke I06 is mounted upon the slide H4 (Figure 4) by means ofthe neck H5. The slide H4 is reciprocable in the guldeway H6 of thebracket H1 (Figures 4 and 7), mounted upon the head I0 of the press anddepending from the extension II8 thereof (Figure 1). The slide H4 isheld in the guideway H6 by means of the retaining plates H9, bolted tothe bracket II1. In Figure 7 the gripper arms I09 are shown engaging aworkpiece I20. This workpiece may obviously be of any character. Forpurposes of illustration the workpiece is illustrated as a cartridgecase for an artillery shell, the press being well adapted for formingthe flanged head upon the cartridge case. The successive stages offorming this cartridge case are shown in Figures 13 to 15, inclusive,and described hereinafter.

Also mounted upon the press head I0 and extending downwardly to the bedII is the control panel I2I. This consists of a sheet metal shield forsupporting the various control elements, switches and gauges utilized inthe control of the press. Mounted upon the control panel [H is thethermometer I22 and the hydraulic press gauge I23, also the push buttonstations I24 and I25 and the switch I26, these'forming parts of theelectrical control system hereinafter described. Also mounted upon thecontrol panel I2I is the tonnage control device I 21. The details of thelatter form no part of the present invention. In effect, it consists ofa pressureresponsive switch having an adjustment for I varying thepredetermined pressure at which the switch becomes operative. Thetonnage control I21 contains a spring-loaded plunger working in a smallhydraulic cylinder and operating an electric switch when the pressure ofthe fluid overcomes the compression of the spring. The springcompression may be adiustecl by turning the hand wheel I28 and therebythe pressure at which the switch becomes operative is varied at the willof the operator. This tonnage control device I21 is connected in serieswith the upper chamber of the main cylinder bore 24 so as to beresponsive to the pressure in the forward side of the hydraulic circuit.

Mountedupon the head I0 is a bracket I29, and disposed below it is asecond bracket I30 for reciprocably guiding the press control rod I3Ihaving thereon a collar I32 adapted to be engaged by the platen arm I33(Figures 2 and 4),

secured, as at. I34, to one of the caps 20 (Figure j 4) bolted to theplaten I5. The control rod I 3I also carries a collar I35, engaged bythe yoke portion I36 of an arm I31 pivotally mounted at I38 upon thecontrol panel I2I, and having the hand lever I39 connected thereto. Thehand lever I39 and the arm I31 have the action of a bellcrank lever formanually raising and lowering the control rod I3I.

The platen arm I33 carries a switch-operating rod I40 (Figure 7), whichin turn, carries a switch-operating cam I M for operating certain limitswitches, as hereinafter set forth in detail in connection with theelectrical construction and operation. Mounted upon the control rod I 3|is a switch-operating cam I42 for operating an additional limit switch,as hereinafter described, while above it'is a collar I43 which engagesthe yoke portion I44 upon the end of a bellcrank lever I45, pivotallymounted as at I46 (Figure 2) upon the bracket I41, bolted to the presshead I 0'. To the other arm of the bellcrank- I45 is attached the rodI48, the opposite end of which is connected to one arm of the bellcrankI49, pivotally mounted as at I50 upon the pump supporting bracket I5Isecured to the press head I0. To the opposite end of the bellcrank I49is connected the rod I52, terminating in the armature I53 of thesolenoid I54. Mounted upon the connecting rod I48 is a member I55engaging the lower end of a rocker arm I56, pivotally mounted at I51upon the pump bracket I5I. To the upper end of the rocker arm I56 isattached the connecting rod I 58, the opposite end of which is connectedto the lever I59 ,plvotally mounted upon the floating link I60 attachedto the pump servomotor I6I. To the opposite end of the lever I59 isattached the servomotor control valve rod I 62, which passes into theinterior of the servomotor I6I and controls the delivery of thereversible variable delivery pump 33 (Figure 2). The reversible variabledelivery pump 33 is of the radial piston type, well known to thoseskilled in the art, and containing a shiftring serving as a flow-controlmember for regulating the direction and amount of delivery of pressurefluid. This flow-control member (not shown) is connected on its oppositeside to a safety centering device I63 (Figure 2) for moving the pumpshift ring or flow-control member to its neutral or no deliveryposition, in the event of failure of power supply to the pump. Thisfeature prevents the coasting down of the platen by its own weight inthe event of such power interruption, and consequent acci dent or injuryto the operator by itsoperating the pump 33 as a motor, and therebyaccelerating the descent of the platen I5. The details of the servomotorI6I and the safety centering device I63 form no part of the presentinvention, and are disclosed in the copending application of WalterErnst, Ser. No. 170,250, filed Oct. 21, 1937. The servomotor "I6Icontains a spring (not shown) which urges the valve rod I62 in onedirection, whereas the energization of the solenoid I54 moves the valverod I62 in the opposite g0 direction by the links and levers describedabove. The turret I4 (Figure 3) is made in two parts forming, in efiect,turret halves which may be bolted together around the single strain rodI2 I in order to facilitate assembly. The turret I4 consists of a hollowcenter post I 64 carrying internal bushings I65 and I66, rotatablysupporting it upon the strain rod I 2. The turret I4 is provided withupper and lower portions I61 and I68, interconnected by the sideportions I69 70 and containing the apertures I10 and HI, re-

spectively, (Figure 3). The various portions of the turret are weldedtogether in the previously described turret halves. Six turret stationsI12 are mounted in the apertures I10 and HI, each of these beingsufficiently strong to sustain the to the press bed II.

entire pressing force of the platen I in complates I13 and rings I14,serving for the attach-" ment of the lower dies. The tubular turretstations I12 are provided with bores I15, closed at their lower ends bythe heads I18 (Figure 3), having bores I11 for receiving the ejectormechanism subsequently described. The turret I4 also carries an annularmember I18 (Figures 3 and 6), to which is secured an internal ring gearI19, held in position by the retaining ring I88 bolted thereto andengaged by a driving pinion I8I on the shaft I82 of the turret-rotatingmotor I83, secured as at I84 to the press bed II. When the motor shaftI82 is rotated, the pinion I8I thereon 'drivingly engages the ring gearI19 and rotates the turret I4. The motor I83 is a direct current motorarranged to provide dynamic braking characteristics, in the mannersubsequently described in connection with the electrical system.

The turret center post I64 carries the upper retaining ring I85 (Figure6) of the tapered roller bearings I88, the lower ring I81 of which iscarried in a socket I88 within a yoke I89 (Figures 4 and 6). The latterextends diametrically across the space beneath the turret I4, and at itsouter ends carries a pair of plungers I98. The plungers I98 areconnected to the ends 01 the yoke I89, through a self-aligningconnection consisting of a stud I9I, threaded into the socket I92 in theend of the plunger I98, this in turn, being rounded as at I93 (Figure 6).and engaging the concavely rounded portion I94 of a disc I95 mounted ina socket I96 in the yoke I89. The stud I9I passes loosely through anenlarged bore I91, and at its upper end is'threaded and carries a pairof retaining nuts I98.

The plunger I98 is reciprocable within the sleeve I99 of theturret-raising cylinder 288, the latter having a chamber 28I to whichpressure fluid may be admitted at the connection 282 through the conduit283. The cylinders 288 are supported upon brackets 284, mounted upon thepress bed II. The plunger I98 is surrounded by a packing 285, engaged bythe ring 288, and in turn engaged by the sleeve 281 mounted in the gland288, through which pass the studs 289, threaded into the cylinder 288and carrying the adjusting nuts 2") upon their upper ends. The packing285 is compressed by tightening the nuts H8. The details of theself-aligning connection I9I to I95 form no part of the presentinvention, and are disclosed and claimed in the copending application ofWalter Ernst, Ser. No. 187,927 filed Jan. 31-, 1938. In order to limitthe motion of the yoke I89, stop rods 2II' are threaded into the sockets2I2 thereof and carry retaining nuts 2I'3, threaded upon their lowerends (Figure 6).

The turret I4 is locked in the positions to which it is rotated andindexed by means of the locking mechanism shown in'Figure 5. For thispurpose the bottom plates I68 of the turret II4 are provided withhardened bushings 2I4, having bores 2 I 5 adapted to be engaged by thelocking pin 2 I6 working in the bore 2I1 of a casing 2I8, boltedThreaded into the lower end of the locking pin 2I8 is a rod 2I9, aroundwhich is arranged a coil spring 228 adapted to urge the locking pin 2I8upward into the bore 2I5 of the hardened bushing 2. The lower end of thecoil spring 228 is engaged by the end of a plug 22I threaded into thesocket 222 at the lower end of the bore 2I1. The rod 2I9 passesoutwardly through a hole 228 in the plug HI, and is adapted to engage apair of limit switches,

the opposite end of the lever 229 is the connecting rod 23I, having itslower end connected to the armature 232 or the locking pin solenoid 238.The solenoid 233 is bolted to the press bed II, and when energized movesthe locking pin 2I6 downwardly, compressing the spring 228 andwithdrawing the locking pin 2; from thebushing 2I4, likewise actuatingthe limit switches, hereinafter described.

The workpiece loosening or ejecting mechanism consists of ahydraulicmotor, generally designated 234 (Figures 3 and 8), having acylinder or casing 235 bolted to the press bed II, and containing acylinder bore 239 having a doubleacting piston 231 reciprocable therein.The piston rod 238 of this piston carries a wear plate 239, bolted tothe upper end thereof. When the piston 'rod 238 is moved upwardly byadmitting pressure fluid to the lower part of the cylinder bore 238, thewear plate 239 enters the hole I11 in the disc I18, which closes thebore I15 of the turret station I12 and lifts the plunger-like lower dieportion 248. The latter extends upwardly into the interior or theworkpiece and engages the internal end thereof, the outer surface of theworkpiece being engaged by the an nular lower die portion I. The dieportions 248 and 2 are separated from one another by an annular space(Figure 8) for receiving the workpiece, such as the cartridge case foran artillery shell.

When the lower die portion 248 is forced upwardly by the piston rod 288,its upper end engages the inner surface of the end 01' the workpiece,forcing the workpiece upwardly and loosening it from its position ofrest between the die portions I and 248. The operator may then operatethe air valve to cause the gripper arms I89 to descend and grip the thusprojecting workpiece I28, as shown in Figure '7. By reversing the valve95 the hoisting piston rod I84 may be caused to ascend, thereby liftingthe workpiece I28 entirely out oi the space between the lower dies 248and 2. The ejector piston rod 238-is provided with an annular shoulder242 for the actuation of a limit switch, hereinafter described, forsynchronizing the action of the ejector mechanism with the remainingmechanism of the press. The piston rod 238 is surrounded by a collar243, surmounted by apacking 244 arranged to be compressed by the gland245 bolted to the casing 235. The cylinder 235 is provided with twoupper ports 246 and a lower port 241. To one of the upper ports 246 isconnected the conduit 18, whereas to the lower port 241 is.-con nectedthe conduit 69, these conduits being connected to the opposite sides ofthe variable delivery pump 33 (Figure 3). To the other upper port 248 isconnected the line 283 leading to the turret-raising cylinders 288,

The main cylinder relief and by-pass valve 84, as stated above, isdisclosed and claimed in the Ernst patent, No. 1,956,758, issued May 1,1934. This valve provides for a drop in pressure within the upper partof the main cylinder 25 at the instant of reversal or the stroke or themain plunger H, such a drop in pressure being necessary before the surgecheck valve plunger 42 can be moved downwardly. The valve 64 also takescare of the discharge of the pump 33 during the fraction of a secondwhich is required for the forcible opening of the surge check valve 31by its auxiliary plunger 58. The main cylinder relief and by-pass valve64 (Figures 9 and 10) contains apair of bores 248 and 249,interconnected by the passageway 258, joining the bore 248 at the port25! and opening into the bore 249 at the port 252. The bore 248 containsannular enlargements or chambers 253 and 254 adapted to besclosed by thevalve piston heads 255 and 256.

The annular chamber 254 is connected to an annular' chamber 251 withinthe lower bore 249, the

latter also having an annular chamber 258 to the left thereof. Valvepiston heads 259 and 268 cooperate respectively with the annularchambers 251 and 258 during the operation of the valve 64.

The valve piston heads 255 and 256 are urged to the right by the coilspring 261, whereas the valve piston heads 268 and 259 are similarlyurged to the right by the coil spring 262. These coil springs 26l and262 engage the inner ends of caps 263 and 264, threaded into thethreaded sockets 265 and 266 of the valve casing 261. The bore 248 isprovided with an additional annular chamber 268, connected to thethreaded port 269 to which the conduit 62 is attached. The chamber 268surrounds the upper valve rod 218 in a similar manner that the lowerannular chamber 251 surrounds the lower valve rod 211. The extremeleft-handend of the bore 248 is provided with a threaded port 212 towhich the conduit 65 is connected (Figure 3). The corresponding threadedlower port 213 is closed by a-threaded plug 214.

Opening into the chamber 253 is a passageway 215, having a threaded portat the end thereof closed by a plug 211. Perpendicular to the passageway215 is a threaded bore- 218, terminating in an unthreaded conicalportion 219 having a similar configuration to the conical portion 288 ofa threaded choke plunger 28 I. The latter may be adjusted by applying awrench to the head 262 so as to regulate the choke passageway be tweenthe portions 219 and 288. The-annular chamber 258 is in /communication,through the ports 283 (Figure\18), with the interior of the surge tank38. Additional ports 284 and 285 for drainage purposes connect the bore248 with the interior of the surge tank 38, as do similar ports 286 and281 opening out of the bore 249.

In order to provide a drop in pressure within "the main cylinder 25 soas to permit the surge check valve 31 to open after the reversal of themain plunger 11 at the end of its working stroke,

and also to take care of the pumpdischarge at a this instant, the maincylinder relief and by-pass valve 64 comes into action. While pressureis still standing within the upper part of the main c'ylinder bore 24,this pressure is also transmitted through the lines 63 and 62 (Figure 3)and the port 269, into the chamber 268 between the piston heads 255 and256. This pressure also passes through the port 25!, the passageway 258and the port 252, into the chamber 288 at the end of the cylinder bore249 adjacent the threaded plug 214, and acts against the piston head259, pushing it together with the valve rod 211 and the piston 268 tothe left, compressing the spring -262. The

shifting of the piston head 268 to the left places,

the chamber 251 in communication with the chamber 258 and its ports 283,The area of the piston 259 and the stiffness of the spring 262 are soproportioned that only a very moderate pressure is required to compressthe spring, for examfile, a pressure of about pounds per square inc Whenthe main plunger I1 is down at the end of its pressing stroke, the upperpart of the main cylinder bore 24 contains a considerable volume of oilunder a very high pressure at the instant that the pump is reversed, forexample, 2500 pounds per square inch. Although the working fluid, suchas oil, is only slightly compressible, there is nevertheless sumcientelasticity in the oil to maintain a considerable. pressure within theupper portion of the main cylinder bore 24 for a fraction of a secondafter the pump 33 is reversed. i At this time, however, the pump 33having been a reversed, is already discharging into the connection 32(Figure 3) and the working fluid or oil cannot enter the lower portionof the main cylinder bore, beneath the main plunger piston head 26,because there is still pressure above the latter. For these reasons,therefore, pressure fluid passes from the connection 32, along theconduits 34 and 65, into the port 212 and end chamber 289 of the uppervalve bore 248. The pressure of this fluid acts against the valve pistonhead 256, pushing it, the valve rod 218 and the valve piston head 2 5 tothe left, compressing the coil spring 26 I. The atter is so proportionedthat only a comparatively light pressure is required to do this.

The shifting of the piston heads 255 and 256 now enables oil to passfrom the pump 33, through the conduits 34 and 65, into the upper endchamber 269, thence through the annular chambers-254 and 251, throughthe lower bore 249, into the annular chamber 256, and thence through theports 283, into the interior of the surge tank 38. In this manner thedischarge of the pump 33 is taken care of at the instant of reversal. Asthe valve piston head 256 is now pushed to the left, communication isestablished between the conduit 62 and the annular chamber 253 by way ofthe port 269, the annular chamber 268 and the upper valve bore 248. Fromthe annular chamber 253 the working fluid or oil escapes (Figure 18)through the passagewayv 215 and the choke passageway between the,plunger 28! and the conical bore 219, into the interior of the surgetank 38. In this manner the pressure is relieved within the; upperportion of the main cylinder bore 24 above the main piston head 26 atthe instant of reversal so as to permit the opening of the surge valve31. The rate at which the pressure will drop within the upper portion ofthe main cylinder bore 24 is governed by the setting of the chokeplunger 2" ,viding too large a choke opening between the portions 219and 268, this too sudden release of pressure will cause an appreciablejump of the main plunger 11 and platen l5, due to the elasticity of thestrain rods l2 and the other press members, as well as that of theworking fluid or oil. The proper adjustment of the threaded chokeplunger 28! prevents an undue jump of the main plunger 11 from thesecauses. When the pressure acting against the piston head 259 in thelower chamber 288 drops sufliciently to permit the coil spring 262 tomove the valve pis= ton heads 268 and 259- -to the right, the by-passaction between the chambers 251 and 258 is terminated. Inthe meantime,however, the drop in pressure within the upper portion of the maincylinder bore 24 permits the surge check valve plunger 42, 43 to bepushed downwardly by the auxiliary plunger 50, thereby opening the surgevalve 31 and permitting oil to pass directly from the chamber above thmain piston head 28, into the surge tank 38. The main plunger I1 andplaten I5 are now free to rise, and are forced upwardly as the pump 33pumps oil into the lower portion of the main cylinder bore 24 beneaththe main piston head 26.

The workpiece I20 may be of any suitable form. A typical workpiece, asshown in Figures 13, 14 and 15, consists of a cartridge case for anartillery shell, resembling a tube of brass, closed by a thick end wall290. Prior to the first operation of the press the upper end of theworkpiece I20 has the rough shape shown in Figure 13. After the firstpressing operation with. the first die, the inner and outer surfaces ofthe end wall 290 are flattened and a rounded portion 29I formed at theedge thereof (Figure 14). The second pressing operation converts thisrounded edge 29I into stepped flanges 292 and 293, with a beveledportion 294 separating the flange 292 from the outer surface of the endwall 290. In this same pressing operation the inner surface of the endwall 290 is provided with a central projection 295-. The tubular sidewalls 293 of the workpiece I20 remain relatively thin in comparison withthe end wall 290 thereof. The operation of the press is obviously notconfined to the production of these tubular cartridge cases, but thelatter is merely shown as a convenient illustration for exhibiting theaction of the press.

Electrical elements The electrical circuit by which the press of thisinvention is controlled is shown in Figures 11 and 12. Figure 11 is anelementary wiring diagram showing more conveniently and more simply thevarious wires connecting the electrical elements with the power lines orsources of electricity, but separating the various contactor or relayswitch blades from their operating coils. Figure 12 is 'the identicalcircuit shown in Figure 11, but the variousswitch blades of thecontactors and relays are placed in their proper positions adja- .centtheir respective operating coils so that the action of these contactorsand relays is more conveniently understood.

The electrical circuit contains a number of contactor switches orrelays, generally designated 30I to 3I0, respectively, the functions oithese being described subsequently (Figure 12).

under the control of the contactors 3I0 and 309, respectivelydistributing current thereto from the three-phase power lines 326, 321and 328 (Figure 12). The action of the pump contactor 3I0 is controlledby a normally open pump start push button switch 329, and by a normallyclosed pump stop switch 330 of the push button type. Each of thecontactors 30I to 3I0 contains a plurality of switch blades,respectively designated a, b, c, etc. in conjunction with the numeraldesignating the contactor switch as a whole. In a few instances thesecontactor switch blades are normally closed upon their contacts, butordinarily they are normally open and are closed by the energization oftheir operating coil, as set forth more in de- I tail under thedescription of the operation.

The control circuit also contains a pair of resistors 33I and 332, inseries with a pair of incandescent light bulbs 333 and 334' forindicating when the circuit is energized. Emergency stop switches of thepush button type are provided at 335, these'be'ing normally closed andmounted upon various parts of the press so as to be convenientlyaccessible to the operator in an emergency. The press control circuit isalso under the control of a stop-run switch 330, and is started by aplurality of cycle start switches 331. These switches 331 are of thepush button type and are normally open. A pair of these push buttonswitches is provided for each operator so that hemust use both hands inoperating .the switches. This arrangement is a safety device forpreventing the operation of the press ,each operator must have .bothhands on the The actions of these contactor switches or relays 30I to3I0 are controlled by a plurality of limit switches, respectivelydesignated 3I I to 320, together with an oil temperature limit switch32I and a tonnage-control switch 322. The'latter is the electricalelement within the tonnage control I21, and is in its effecta'pressure-responsive switch. The electrical circuit of Figure 12 alsocontains a pump motor 323 for driving the variable delivery pump 33 anda motor 324 for driving' the direct current generator 325, the lattersupplying direct current for actuating the turret-rotating motor, I83.The provision of this motor generator 324, 325 enables the use of thedynamic braking characteristics of the direct current motor I83 forslowing down and dynamically braking the turret I4 as it approaches itsindexing positions. The motors 323 and 324, however, are actuated byalternating current to be actuated by a single operator.

switches before the press will start in operation. The foreman in chargeof the machine can set the press for a single or a pair of operators bymanipulating the operator switch 338, whereby a pair of switches 331 maybe shunted out of the circuit, leaving but a single pair of switchesAdditionally provided is a normally'open push button type .switch,designated the die reset switch 339, and

a second normally open push button switch, designated the reset switch340. The latter is associated with the emergency stop switches 335adjacent the contactor 30I in Figure 12.

The locations of the various limit switches are as follows: Associatedwith the turret-locking mechanism (Figure 5) are the limit switches 3Hand m, these being actuated by the motion of the rod H9 in response tothe upward and down-' ward motion of the locking pin 2I6. Associatedwith the turret and operated by a cam 3 on the periphery thereof (Figure4) is the limit -switch 320. Adjacent the limit switch 320 is the limitswitch 3I3, operated by the cam 342 (Figure 4). likewise on theperiphery of the turret I4. The cam 34I actuates the limit switch 320 asthe turret I4 approaches one of the indexing positions, in order tooperate the dynamic braking circuit and slow down the turret I4, ashereinafter explained. The cam 342, however, op-

.erates the limit switch 3I3 when the turret I4 arrives at the indexingposition to deenergize the solenoid 233 (Figure 5) and permit theturret-locking pin 2 I8 to be urged upwardly by the coil spring 220 andenter the locking bushing 2I4,

thereby locking the turret 14 in its indexed position. 7

Associated with the die-carrier .11 and operated thereby are the limitswitches 314 and 315 (Figure 4). These limit switches control thecircuit by insuring that the die-carrier 11 has reached the properposition as operated by the air cylinder 82- before the remainder of thepress mechanism can operate. Associated with the platen-shifted controlrod 131 (Figure 7) and operated thereby is the limit switch 316, thisoperating being brought about by the cam 142. Associated with the platenarm 133 and operated by the cam 141 upon the rod 140 thereof are thelimit switches 311 and 318 (Figure '1). Associated with the ejectorplunger 238 and operated by the annular shoulder 242 thereon (Figure 8)is the'limit switch 319. The limit switch 320, as previously stated, isassociated with the limit switch 313 and actuated by the rotation of theturret 14. The limit switch 321 is a tempera ture-responsive normallyclosed switch, which is exposed to the temperature of the oil and whichoperates automatically to open when the oil temperature exceeds apredetermined maximum. In

this manner the overheating of the oil, which tactors, relays, etc. arearranged behind the control panel 121, which is made in box-like form toinclos'e them.

Associated with the field coils 343 and 344 is the resistor 345, andassociated with the armature 346 is the resistor 341. The turret motorshunt field 348 is not subject to the action of these resistors. Avoltmeter 349 and ammeter 350 indicate the condition of the circuitactuating the direct current turret-rotating motor 183. The varioussolenoids for operating the valve which controls the actions of thefluid pressure motors have already been described, and consist of thedie-carrier valve-operating solenoid 89 (Figure 1), the servomotorcontrol solenoid 154 (Figure 2) for actuating the servomotor controlvalve rod 162 of the servomotor 161 which actuates the shiftring orflow-control. member of the variable delivery pump 33 and the lockingpin solenoid 233 (Figures 1 and 5) An off-on switch 351 is arranged inseries with the limit switch 316 with the action as hereinafterdescribed.

Operation Referring to Figure 12, the operator starts the pump 33' bymomentarily depressing the pump start switch 329. This energizes thecontactor V switch 310 and closes its normally open blades the stop-runswitch 336, which energizes the v motor generator contactor 309 andcloses its normally open blades to energize the motor generator motor324. At the same time the indicating lamps 333 and 334 show that thecircuit is energized. The motor generator 324, 325 then starts inoperation to energize the direct current circuit shown at the bottom ofFigure 12 for actuating the direct current turret-rotating motor 183.

The foreman, having determined whether one or two operators shalloperate the press, sets the switch 338 either closed for a single orator or open for a pair of operators. Before the cycle start buttons33], controlled by the switch 338, can become operative, however, it isnecessary for the operator to energize the contactor 3111 by momentarilyclosing the push button type reset switch 340. The latter closes acircuit through the normally closed emergency stop switches 335, andthis action closes the three normally open switchblades 3111, 301 and301 of the contactor 301. The closing of the switchblade 301 energizes aholding circuit to maintain the energization of the contactor 301 whenthe reset switch button 340 is released. The shifting of the switchblade301 closes the circuit of the turret motor control relay 304, which hasan alternating current relay handling the direct current through itssingle switchblade 304. The closing of the normally open switchblade 304energizes the contactors 301 and 308, controlling the direct currentturret-rotating motor 183. The third switchblade 3111 of the contactor301 controls the circuit leading to the servomotor control solenoid 154and to the portions of the circuit shown in Figure 12. If at any timeone of the emergency stop switches 335 is depressed, the opening of thecontact thereof deenergizes the contactor 301 and opens its contacts,deenergizing the previously-mentioned circuits. It is then necessary forthe operator to depress the reset switch button 3411 again in order toreenergize the contactor 301.

An operator now places an unfinished workpiece (Figure 13) in the turretstation 1'12 between the outer and inner lower die members 241 and 240.The workpiece is placed in the turret station that is ready to enter thepress and be advanced to the pressing position. The operating cycle isthen started by pressing either two or four of the cycle start buttons331, depending upon whether one or two operators will operate the press,as determined by the setting,

of the switch 338. In either case, the provision of the switches insuresthat both hands of each operator are out of the working area of thepress before starting the cycle of operations. The depressing of thecycle start buttons 331 closes a circuit through the normally closedlimit switch 313, and likewise through the limit switch 319, the latterinsuring that the ejector pin 238 is down (Figure 8). The circuit isthereby energized through the operating coil of the contactor 302 whichcontrols the locking pin solenoid 233. The normally open switchbladesthereof close and the upper switchblade 302 operates a holding circuitaround the cycle start buttons 331 so as to maintain the energization ofthe contactor 302 when the operator or operators have released the cyclestart buttons 331. The closing of the contactor 302 energizes thelocking pin solenoid 233 through the now closed switchblades 302 and302, causing the locking pin 216 to be withdrawn from its lockingposition and compressing the coil spring 220 (Figure 5). The closing ofthe switchblade 302 energizes the operating coil of the die contactor303 through" the normally closed limit switch 3". The latter is openedwhen the main plunger I1 and platen I reach their downward position,thereby providing a safeguard against the operation of the itdie-carrier 'I'I when the platen I5 is down. The

upper switchblade 303, when closed, establishes a holding circuit tomaintain the energization of the contactor 303 after the contactor 302has been deenergized. The normally open switchbiade 306 is placed inparallel with the limit switch 3, and operates in the manner describedbelow.

The withdrawal of the locking pin 2L6 closes the contacts of thenormally open limit switch 3 (Figure 5), thereby closing the circuitthrough the normally closed Switchblade 300 (which is closed when theplaten I5 is up); the now closed switchblade 3M; the now closed limitswitch 3l9 (which has been permitted to shift to its normally closedposition by the withdrawal of the elector plunger 238) and the operatingcoil of the turret motor control relay 304. The energization of therelay 304 closes its normally open switchblade 304 and energizes thecontactors 301 and 300 with direct current from. the direct currentgenerator 325.- The closing of the ccntactors 301' and 300 energizes theturret-rotating motor I83 and starts it in operation. The normallyclosed limit switch 320 is now in a closed position at this point of thecycle because it is not yet opened bythe cam 345. The closing of theswitchblades 301* and 308 in series with the armature and fields of theturret motor I83, brings the motor I03 into operation at full speed atits full voltage. The switchblades 30'! and 301, however, are normal- 1yclosed, hence, will be open at this point in the cycle.

The operation of the the turret until it approaches its indexingposition, whereupon the cam 3 (Figure 4) opens turret motor I03 rotatesthe limit switch 320 and holds it open temporarily. This actiondeenergizes the operating coil of the contactor 301 and therebyopens'its normally open switchblade 301* while closing its normallyclosed switchblades 301 and 301. This action places the resistor 34! inparallel with the motor armature 300 and commutatlng field 303, and alsothe resistor 341 in series with this combination. The resistance thusintroduced into the turret motor circuit causes the speed of the 5), andis pushed into the aperture 2|! by the spring 220. This looks the turretI4 in its working position. The motion of the locking pin 2 into thebushing 214 permits the normally closed contacts of the limit switch 3l2to close, thereby placing the circuit in readiness for the downward orpower stroke of themain plunger l1 and platen Ill. The closing of thecontacts of the limit switch 3l2 energizes the operating coil or theccntactor 305 by way of the now closed switchblades 30I and 303*. Theswitchblade 305' is connected in parallel with the contacts 01 theswitchblade 303 and the normally closed contacts of the limit switch 3I8so as to form a holding circuit for the operating coil of the contactor305, even it the operating coil of the contactor 303 is laterdeenergized. The contacts of the ;-witchb1ade 306' are also in parallelwith the limit switch 3I8, the latter being normally closed but openedby the (Figure '7).

The closing of the contacts of the limit switch 3|! also completes thecircuit to the oiI-on selector switch L With the latter switch in its onposition it is possible to operate the turret l4 without operating themain plunger II, so as to set up the machine or make necessaryadjustments in the operation of the turret. With the closing of theselector'switch 35!, however, the circuit will be completed to theoperating coil of the ram control contactor 305 through the contacts ofthe normally open limit switch 3l0, which is now held closed by thecontrol rod cam I31 (Figure 7) because the main plunger I1 is in its upposition. The circuit, which is thus closed, continues from the limitswitch 3I0, through the now closed contacts of the normally open switch3, this being held closed by its engagement with the die-carrier 11 whenthe latter has moved into its proper position. this indicating that thefirst upper die is aligned with the lower die. The thus closed circuitcontinues through the now closed contacts of the switchblades am and suand the normally closed oil temperature limit switch 32I. Theenergization of the operating coil of the contactor 308 closes thecontacts of the switchblades 306' and 306 turret motor I83 to be greatlyreduced, for example, to about twenty-five per cent. otits normal speed,thereby slowing down the turret II- as it approaches its next position.Just prior to reaching the next position the turret ll, by its cam 342,causes the limit switch 3I3 to be momentarily opened. therebydeenergizing the contactor 302 and the locking pin solenoid 233, thuspermitting the spring 220 thereof (Figure 5) to push the locking pin 2l6upwardly until it rests against the turret bottom portion I68.

This slight motion of the locking pin 2I0 is sufflcient to permitthenormally open limit switch 3 to open, thereby deenerglzing theoperating coil of the contactor 303.

The consequent opening of the Switchblade 304'- breaks the circuitthrough the operating coils of the contactors 301 and 308. This actionleaves the resistor 345 connected across the armature circuit of theturret motor I83, thereby causing the latter to dynamically brake theturret I4. The latter, however, has suflicient momentum to carry itaround until the locking pin 2" arrives opposite the bushing 2| (Figurethereby completing the circuit through the servomotor control solenoid I50.

The energlzation of the servomctor control solenoid I50 shifts theservomotor control valve me 82, causing the pump servomotor to move itsshift-ring or flow-control member into its forward delivery position.The pump 33 then pumps oil from the surge tank 38, through the checkvalve 61 and conduit 34, and also from the main cylinder bore beneaththe main piston head 28, through the conduit 30, into the conduit 29leading to the main cylinder 25 above the piston .head 26. This causesthe main plunger l1 and platen IE to descend. These will move downwardlyby gravity as fast as oil is removed from beneath'the piston head 25,and the void above the piston head 26 will be fi1led-by oil passing fromthe surge tank through the surge valve 31, V

which has meanwhile opened. The switchblade 306 is placed in series withthe contacts of the pressure switch 322, and this maintains a circuit tothe operating coil of the contactor 308 after the contacts of the limitswitch 3I0 have opened. The limit switches 3|! and 3! are so platen armcam Ill I40 extending upwardly from the platen arm I33. This has noeffect upon the circuit because they are in parallel with the contactsof the now closed switch blades 306 and 306 respectively.

As the platen I5 moves downwardly and engages the workpiece, pressureconsequently is built up in the upper part of the main cylinder andreverses the setting of the pump flow-control member, thereby reversingthe pump. The latter then is in position to pump the oil from the spaceabove the main piston head 26 and into the space below the main pistonhead 26.

The latter space, however, is much smaller than the space above thepiston head 26, but this surplus oil is taken care of by the forcibleopening of the surge valve 3? by the auxiliary plunger 50 by means ofpressure fluid received through the conduit 34 from the return side ofthe pump circuit. The opening of the surge valve 31, of course, takes.place after the main cylinder relief and by-pass valve. 64 is operatedto reduce the pressure in the main cylinder bore 24 above the mainpiston head 26, and temporarily to by.- pass the discharge of the pump33 in the manner described above in connection with the construction ofthe valve 64. When the pressure has been sufiiciently reduced by theaction of -the valve 64 the check valve 31 opens and permits oil to flowfreely from the main cylinder 25, directly into the surge tank 38.

As the platen I5 moves upwardly the normally closed limit switches 3I1and 3I8 are again opened momentarily as the up stroke of the ramproceeds. The opening of the limit switch 3I8 has no effect since it isstill in parallel wit-h the contactor switchblade 303. As the contactor306 is now deenergized, the contacts of its switchblades 306 and 306 arenow open. The opening of the limit switch 3II, however, deenergizes theoperating coil of the contactor 303 and consequently opens the contactsof its switchblades 303 and 303 to deenergize the die-carrier valvesolenoid 89. The operating coil of the contactor 305, however, remainsenergized through the.

cylinder 82, causing the second upper die to be shifted to the positionformerly occupied by the first upper die through the reciprocation ofthe die-carrier TI.

The shifting of the die-carrier I1 releases the normally open limitswitch 3 and permits it to open, at the same time closing the normallyopen limit switch 3|5. As soon as the main plunger I1 and platen I5reach their top positions, so as to close the limit switch-'3l6 by meansof the control rod cam I42, a circuit is established through the nowclosed switch blade 30!", the now closed limit switch 3I2, which hasbeen permitted to close by the advancement of the turret-locking pin 2I6into the locking bushing 2, the off-on selector switch 35I, which isassumed to have been closed by the operator, the normally open limitswitch 3I6 (now held closed by the control rod cam I42) the limit switch3I5 (normally open but now held closed by the diecarrier 11), the closedcontacts of the switch blades 3113 and 305 the operating coil of thecontactor 306 and the oil temperature limit switch 32L When thecontactor 306 is thus energized it closes the contacts of its switchblades 306 and 306 thereby energizing the servomotor control solenoidI54 and shifting the control of the pump 33 so as to deliver pressure tocause the main plunger I! again to start a down stroke for the secondoperation upon the workpiece. After the first operation the workpiece,it will be recalled, has the appearance shown in Figure 14. The secondoperation now gives it the appearance of Figure 15, as previouslydescribed. At this time, however, because the operating coils of thecontactors 302 and 303 are deenergized, the contacts of their switchblades 302 i and 303 are open so that no circuit can be completedthrough the limit switch 3| I or the switch blade 306 to the operatingcoil of the contactor 303. The latter, therefore, remains deenergizedand its switchblade 303 is open, but the operating coil of the contactor305 is held in its previously energized condition by reason of theholding circuit established through its upper switchblade 305 and'thelimit switch 3 I8. Therefore, even though the normally closed limitswitch 3I8 is opened by the cam MI upon the descent of the platen I5 andplaten arm I33, it will have no effect upon the remainder of the circuitbecause it is in parallel with the then closed contacts of theswitchblade 306*. The opening of the limit switch 3I'I by the sameaction also has no effect because the circuit through this limit switchhas already been opened.

The main plunger I! and platen I5 move downwardly until the second upperdie engages the workpiece and performs a pressing stroke, whereuponpressure is again built up to the setting of the pressure switch 322,thereby opening the latter. The opening of the pressure switch 322deenergizes the operating coil of the con- 1 tactor 306, and as aconsequence deenergizes the servomotor control solenoid I54, causing thedelivery of the pump 33 to be reversed, whereupon the main plunger i1 isretracted, as previously explained, and returns to its upper position.Since the contacts of the switchblades 303 and 306 are now open,however. the opening of the limit switch 3I8 on the up stroke of themain plunger. I! now causes the operating coil of the contactor 305 tobe deenergized. This opens the contacts of the switchblade 305 so thatwhen the main plunger I! has returned to its top position and thecontrol rod-cam I42 has closed the normally open limit switch 3I6, nocircuit is completed and the servomotor control solenoid I54 will not beenergized. Accordingly, the main plunger I1 and platen I5 remainstationary in their retracted position. The next cycle of operation ofthe press is started by pressing the cycle start buttons 331, in themanner previously described, after which the platen I5 will againautomatically perform a pair of pressing strokes with the first andsecond upper dies as previously

